Pressure operated valve



March 2, 1948.

yw. o. LUM

PRESSURE OPERATED vVALVE:

File@ March 15, 1944 f /R Inventor:

- Wa'LIcJer` O. Lum,

b5 JV w/w His Atborhqg.

MIIB

PRESSURE mm VALVE Walter 0. Lum, Schenectady, N. Y., assigner to GeneralElectrl Nh York eCemrlnzaeorrmtienor Application March 15. 1944, SerialNo. 523,5

4 Claims. (Cl- 137-153) Forcertainapplicationaitisrequiredthatanumberoffuelnozzles. eachsupplyingfueltoa separate combustion chamber,kbe connected in parallel to a common fuel header and that during theoperation equal amounts of fuel over awiderangeofoperationfromnoloadtofull load be supplied from the header toeach fuel nozzle. It is further required that upon changes Y in load.the fuel supply to all the fuel nozzles be varied evenly. promptly andsimultaneously. Buch an application is met with. for example, in thecase of gas turbine power plants wherein a number of relatively smallcombustion chambers (for example as many as 12 or more) arranged in acircle supply gas to a turbine wheel, each combustion chamber supplyinggas to a small arc of the wheel. In such an application, it is lmportant that the wheel be equally loaded throughout its circumferencewhich means that each combustion chamber at all loads must supply equaltemperatures of gas to the nozzles of the turbine. It is also n thatfluid fuel be metered very accurately to the combustors over anextremely wide range of flow rates. v

The object of my invention is to provide an improved fuel distributingsystem and an improved fuel nozzle for use therein for meeting theforegoing requirements, and for a consideration of what I believe to benovel and my invention, attention is directed to the followingspecification and to the claims appended thereto.

In the drawing. Fig. 1 is a diagrammatic view of a system embodying myinvention, and Fig. 2 is a longitudinal sectional view through one of myimproved fuel nozzles.

Referring to the drawing, I indicates a fuel tank connected by a pipeline 2 to the inlet of a suitable fuel pump I which has its dischargeside 4 connected to a fuel header I. In the case of an installationwherein a number of combustion chambers are arranged in a circle, headerI may be in the form of an annular pipe to which the fuel nozzles of theseveral combustion chambers are connected. In the present instance, byway of example, I have shown three fuel nozzles 2 pipe line I by aby-pass pipe II in which is located a suitable hand control valve II.When hand control valve II is open. fuel discharged from pump 4 canivy-pass through pipe I0. s, and2backtopumplandthesupp1ytankl so thatwhen valve II is open. no fuel oil is supplied to header I. As valve IIis closed. fuel oil will be supplied to header I, its pressure beinggradually increased as the valve moves toward closed position. Thus,valve II forms a control valve for resulating the amount of fuelsupplied to header I and the pressure in the header.

Each fuel nozzle I may supply fuel to a separate combustion chamber. Thefuel nomle may be of a type in which-fuel is atomized to the combustionchamber by pressure alone or it may be of a type in which it is atomizedby means I connected to header I in parallel, this being intended torepresent any suitable number of fuel nozzles connected to a header ofany suitable type. The branch pipes connecting header I to of air. Inthe present instance, the latter arrangement has been illustrated, I2indicating a pipe line leading from a suitable source of air pressure.Referring to Fig. 3, II indicates a cylinder in which is mounted one endof an elongated hollow piston II. In the h ead of cylinder I5 is adischarge opening I'I with which a pipe 8 connects. In the dischargeopening is a plug I8 having a central opening II for ilow of fuel oil toopening I'I. Plug II is provided with a threaded stem 2I on which is anut 2| with which engages one end of a spring 22. The other end ofspring 22 is located inside piston II and engages head 23 of the piston.Plug II is provided with a suitably shaped socket in its left hand endto receive a tool for turning the plug. By turning plug II, nut 2| maybe moved longitudinally of cylinder II to adjust the compression ofspring 22, the nut being held from turning by reason of its engagementwith the end of the spring. The right hand end of cylinder II (Fig. 2)is counterbored to provide a fuel oil supply chamber 24 with which afuel oil supply pipe I connects. In fuel oil supply chamber 24 is asuitable filter screen 25 carried on a metal framework 2I. From theabove described arrangement, it will be seen that the right hand face ofthe head 23 of piston II is subjected to the pressure of the fuel oilsupplied through pipe 1. In the wall or sleeve portion of the hollowpiston I6, just in advance of the shoulder formed in cylinder I I by thecounter-bored end, is an opening 21 which connects fuel oil chamber 24with the interior of cylinder I5 and hence with discharge pipe I.Connected to the right hand open end of cylinder I5 by means of asuitable coupling III is a cylinder II, the end I2 of which is providedwith eled edge at the right hand open end of cylinder I5 to make a tightflt with cylinder 3l and seal against the open end of cylinder i5. Thissealing arrangement is more fully described in my copending application,Serial Number 526,583, filed March 15, 1944. The outer surface of post36 in connection with cylinder 3i forms an air chamber 38 with whichconnects'the air pipe line I2. Inside post 36 is a spool 33 having adischarge opening surrounded by a valve seat with which engages thepointed end of a fuel oil metering pin 40, such pointed end forming avalve head 403. Metering pin 43 projects out through a iluid controlopening in bushing 4I threaded into(y the end of post 33 and is providedwith a y head 42 by which it is suitably attached to the 1 right handend of piston I6. In metering pin 40 is a longitudinally extendingmetering groove 43 which increases gradually in size from the left handend of the metering pin toward the right hand end. Between spool 33 andatomizing head 32 there is a fuel oil chamber 44 which is connected bypassages 45 to air flow passages which connect air chamber 38 with theswirl chamber 35. These air passages each comprise an axially extendingportion 43 formed in the peripheral portion of the swirl head and atangentially extending portion 41, the fuel passages 45 communicatingwith the tangentially extending portions 41. With this arrangement, thefuel and air enter the swirl chamber tangentially, thus setting up aswirling movement of the air and fuel in the chamber to provide athorough mixture before the fuel and air are atomized through theopening 33 to the combustion chamber. At 43 is a suitable coupling meansby which the fuel nozzle may be fastened in the wall of a combustionchamber.

The operation is as follows:

Assume that fuel oil pump 3 is operating and that valve Il is open.Under these conditions, the oil discharged from pump 3 will flow throughby-pass I0 back to pump intake line 2, nov oil pressure being built upin header 5. The pointed heads 40a of metering pins 40 in each of thefuel nozzles will be against its seat, closing the discharge opening inspool 33. Now, as valve Il is moved toward closed position, oil will bedirected to header 5 and will be supplied from header 5 to each of thefuel nozzles through pipes 1. The fuel oil entering a nozzle throughpipe 1 builds up a pressure in fuel oil chamber 24 which pressure actson cylinder head 23 in a direction tending to move it toward the left tomove the head of the metering pin away from its valve seat. At the sametime oil ows through by-pass opening 21 in the wall of cylinder i3 tothe return pipe 3. As valve Il is moved further toward closed position,a pressure will be built up in the fuel oil chamber 24 suillcient tomove piston I6 against the action of spring 22; and, after apredetermined short movement, by-pass opening 21 is covered by thecylinder wall. When this happens, the pressure is built up more quicklyin oil chamber 24 since a part of the oil can no longer escape throughby-pass opening 21. As a result, the metering pin 40 is moved quickly toa definite metering position to admit fuel to fuel chamber 44, fromwhence it is discharged through openings 45 in the'atomizing head toswirl chamber 35. Inthe swirl chamber 35 the fuel is mixed with airunder pressure conducted thereto from the air chamber 33 through thepassages 45, 41. The mixture finally is discharged through the sprayopening 33 into a combustion chamber or other consumer. The meteringpins of all the fuel nozzles will be moved by the same amount whichmeans that each will be feeding an equal amount of fuel to itscombustion chamber. Now, as the pressure is increased and decreased bymoving valve Il toward closed and open positions, the pressure in header5 is varied and the amount of fuel supplied by each fuel nozzle to itscombustion chamber varied. The fuel flow in each nozzle is controlled bythe axially extending metering groove 43, cooperating with tre fluidcontrol opening in bushing 4|, and' by the pressure of the fuel oil.Because of the comparatively long travel of metering pin 40, accuratemetering of fuel over a wide range of flow rates is possible by carefuldesign of the contour of slot 43.

There is a substantial drop in oil pressure in the fuel oil as it flowspast the metering pin and through spool 33 to fuel oil chamber 44.` As aresult, the difference in head due to the fuel nozzles being connectedinto header 5 at different points has a negligible effect on thedistribution of the oil to the respective fuel nozzles. It will beunderstood that initially the springs 22 of the several fuel nozzles areadjusted relative to each other so that all the fuel nozzles operate ina like manner.

When valve Il is opened to shunt the flow of fuel oil from header 5, assoon as the by-pass opening 21 reaches a point where it communicateswith fuel oil supply chamber 24, the oil pressure in the supply chamberis quickly released through opening 21, thus permitting the metering pinto move quickly to its final closed position. Due to this arrangement,the fuel nozzles, when being put out of operation, will all be quicklyand simultaneously moved to their closed positions thus insuringpositive shut-off of fuel oil to all the combustion chambers. This isone important feature of my invention since it does away with thepossibility of fuel oil being supplied to certain of the fuel nozzleswhile others are entirely closed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In a variable pressure wide-range fluid metering device, thecombination of a casing having walls forming a bore including an inletchamber and a fluid control opening and a discharge opening in seriesilow relation, an axially slidable metering pin disposed in the bore andadapted to project at least partially into and cooperate with thedischarge opening, said metering pin having a rst portion cooperatingwith the dis-v charge opening to form a positive shut-ofi valve and asecond axially spaced portion shaped to define with the fluid controlopening a variable area metering orifice in series flow relation withthe shut-off valve, means responsive to pressure in the inlet chamberfor positioning the metering Din to consecutively open the shut-offvalve and then vary the size of the metering orifice as a predeterminedfunction of increasing inlet chamber pressure, said pressure responsivemeans including a piston connected to the metering pin and slidablydisposed in said bore with an outer end surface subjected to fluid inletpressure tending to move the piston toward metering position,

of positions adjacent the valve-closed position,

whereby the piston is caused to move quickly between the valve-closedposition and the minimum flow metering position.

2. In a variable pressurey Wide-range fluid metering device, thecombination of a casing having walls forming a bore including an inletcham- Iber and a fluid control opening and a discharge opening in seriesflow relation, an axially sutiable metering pin disposed in the bore andadapted to project at least partially into and cooperate with thedischarge opening, said metering pin having a first portion cooperatingwith the discharge opening tio form a positive shut-off valve and asecond axially spaced portion shaped to define with the fluid controlopening a variable area metering orifice in series ow relation with theshut-E valve, means responsive to pressure in the inlet chamber forpositioning the metering pin to consecutively open the shut-off valveand then vary the size of the metering orifice as a predeterminedfunction of increasing inlet chamber pressure, said pressure responsivemeans including a piston connected to the metering pin and slidablydisposed in said bore with an outer end surface subjected to uid inletpressure tending to move the piston toward metering position, meansbiasing the piston to valve-closing position, means for adjusting saidbiasing means, the shape of said second portion of the metering pinbeing so related to the fluid control opening that a metering orifice isformed only during the occurrence of a pressure in the inlet chamberabove a preselected minimum value, said piston having a restricted portarranged to communicate uid from the inlet chamber to the opposite sideof the piston only when the piston is within a llimited range ofpositions adjacent the closedvalve position, whereby the piston iscaused to move quickly between the valve-closed position and the minimumflow metering position.

3. In a variable pressure wide-range fluid metering device, thecombination of a casing forming an inlet chamber and a fluid controlopening and a discharge opening in series flow relation, an axiallymovable fluid metering pin disposed in the casing and havingan endportion adapted to cooperate with the discharge opening to form apositive shut-oil.' valve and an intermediate portion shaped to definewith the fluid control opening a metering orifice of a size variable asa preselected function oi the axial position of the pin, a cylinderformed in the casing and communicating with the inlet chamber, a pistonslidably disposed in the cylinder with an outer end surface subjected tofluid inlet pressure and connected to the metering pin, means in thecasing biasing the piston to a position wherein the metering pincooperates with the discharge opening to positively stop the flow ofiluid, and a restricted passage arranged to by'- pass fluid from theinlet chamber to the opposite j and arranged to be closed by initialmovement of the piston when nuid pressure in the inlet cham. ber risesto a preselected value whereby the piston is caused to move quickly to afluid-metering position.

' 4. In a variable wide-range fluid metering device, the combination ofa casing having a longitudinal bore with a iluid discharge port adjacenteach'end thereof, a hollow piston member slidably disposed in a portionof said bore and having an open end communicating with one of saiddischarge ports, walls dening iiuid inlet passages arranged tocommunicate fluid inlet pressure to the outer end surfaces of the pistonremote from said open end, said bore having a second portion forming rstand second axially spaced openings, the first being a fluid controlopening arranged to communicate with said inlet passages and the secondbeing a discharge opening arranged in series flow relation between thefirst opening and the other of said fluid discharge ports, metering pinmeans projecting through said first opening and connected to the pistonto be positioned thereby, said pin having a first portion shaped tocooperate with the first uid control opening to deilne a variable oriceof an area which varies in a preselected manner as a function ofmetering pin position, the pin also having an axially spaced end portionconstructed and arranged to cooperate with the second opening to form apositive shut-oi! valve, and means.

associated with the piston for biasing the metering pin to valve-closingposition, said piston having a side wall portion dening a restrictedbypass port communicating between the inlet passages and the interior ofthe piston, the location of the by-pass port being so related to theconguration of the metering pin that initial movement lof the pistonfirst opens the shut-olf valve and then covers the by-pass, whereby thepresysure differential across the piston is increased to quickly movethe pin to a fluid metering position.

WALTER O. LUM.

REFERENCES CITED The following references are of record in the flleofthis patent:

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sinks July s, 1929

